Catalytic processes for the conversion of hydrocarbons are well known and extensively used. Invariably catalysts used in these processes become deactivated for one or more reasons. Where the accumulation of coke deposits often causes the deactivation, reconditioning of the catalyst to remove coke deposits helps restore the activity of the catalyst. Coke is normally removed from catalyst by contact of the coke-containing catalyst at high temperature with an oxygen-containing gas to combust and remove the coke in a regeneration process. These processes can be carried out in-situ or the catalyst may be removed from a vessel in which the hydrocarbon conversion takes place and transported to a separate regeneration zone for coke removal. Arrangements for continuously or semi-continuously removing catalyst particles from a reaction zone and for coke removal in a regeneration zone are well known.
In order to transport catalyst from a reaction zone containing hydrocarbons to a regeneration zone containing oxygen, the two zones are ordinarily connected by one or more lines or conduits. The two zones generally operate at different pressures and contain different fluids which preferably are inhibited from communicating with one another.
Accordingly, various devices are provided for separating the catalyst from the hydrocarbon products, and for providing a fluidized stream of catalyst to the regeneration zone. One such device is known as a lift engager. An exemplary lift engager is shown in U.S. Pat. No. 5,338,440 the entirety of which is incorporated herein. Such lift engager comprises a pair of concentric conduits within a vessel. In the annulus between the concentric conduits, the outer conduit provides a gas that is used, inter alia, to lift catalyst particles out of the vessel through the inner conduit.
While such devices are presumably effective for their intended uses, conventional lift engagers utilize concentric conduits that are both fixed. In other words, within the vessel, the length of the conduits cannot be easily adjusted. Furthermore, after installation, once the processing unit with the lift engager is operating, it is time consuming and arduous process to adjust the length of the conduits. Additionally, the processing unit must be stopped or at a minimum have its throughput reduced so that the vessel is disassembled. Once the vessel is disassembled, one or both of the conduits are permanently cut with tools.
Therefore, there remains a need for a lift engager that does not require such a time consuming process in order to adjust the conduits of the lift engager. It would particularly be desirable to also provide a lift engager that did not require the processing unit to be shut down when adjusting the length of the conduits.